Revert of clang/win: Stop passing -Qunused-arguments.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 7693cf1e416fb0f5381c2ad61e91a21dae29fc80..f476e323492a1e8e7349a72492714a549f4b6de4 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -5633,13 +5633,6 @@
                     'Optimization': '2',
                     # 1, favorSpeed - Favor fast code (/Ot)
                     'FavorSizeOrSpeed': '1',
-                  },
-                },
-              }],
-              # TODO(thakis): Remove clang==0 here, https://crbug.com/598772
-              ['optimize=="max" and clang==0', {
-                'msvs_settings': {
-                  'VCCLCompilerTool': {
                     # This implies link time code generation.
                     'WholeProgramOptimization': 'true',
                   },
@@ -5751,6 +5744,7 @@
           'VCCLCompilerTool': {
             'AdditionalOptions': ['/MP'],
             'MinimalRebuild': 'false',
+            'BufferSecurityCheck': 'true',
             'EnableFunctionLevelLinking': 'true',
             'RuntimeTypeInfo': 'false',
             'WarningLevel': '4',
@@ -5823,14 +5817,6 @@
             }],
           ],
           'conditions': [
-            ['clang==0', {
-              'VCCLCompilerTool': {
-                 # TODO(thakis): Enable this with clang too,
-                 # https://crbug.com/598767
-                 'BufferSecurityCheck': 'true',
-              },
-            }],
-
             # Building with Clang on Windows is a work in progress and very
             # experimental. See crbug.com/82385.
             # Keep this in sync with the similar blocks in build/config/compiler/BUILD.gn
@@ -5849,6 +5835,7 @@
                   '/FIIntrin.h',
 
                   # TODO(hans): Make this list shorter eventually, http://crbug.com/504657
+                  '-Qunused-arguments',  # http://crbug.com/504658
                   '-Wno-microsoft-enum-value',  # http://crbug.com/505296
                   '-Wno-unknown-pragmas',  # http://crbug.com/505314
                   '-Wno-microsoft-cast',  # http://crbug.com/550065